In the field of inertial sensors, increasing cost and performance demands are being placed on proven existing systems, such as electromechanical instruments and, more recently, ring laser gyroscopes. Currently, efforts are being placed on improving newer technologies, such as interferometric fiber-optic gyroscopes (IFOG). The emphasis today is not so much on improving sensor performance, as meeting other practical demands such as reducing system size while lowering material and assembly costs. While ring laser gyroscopes are finding continued commercial success in specialized applications, interferometric fiber-optic gyroscopes have not achieved the potential that was hoped for at their inception. Unit costs and construction difficulties have been cited as areas for improvement.
Thus, a need exists for improving construction materials and techniques used to produce interferometric fiber-optic gyroscopes. For example, cost savings are possible with single mode components, although depolarizers and other additional components may be required to prevent signal deterioration. Further, there is a need for improved construction of interferometric fiber-optic gyroscopes using cost effective techniques such as those associated with integrated circuit technology. U.S. Pat. No. 5,377,283 is directed to the configuration control of mode coupling errors, and points out added complications, such as second order dispersion effects, which result when an integrated optic chip, such as one having a substrate formed of lithium niobate, is employed in a fiber optic circuit. This patent also employs a circuit in which both single mode and polarization maintaining optical fibers are employed, along with depolarization remediation attained by splicing first and second polarization maintaining optical fibers. Depolarized fiber optic gyroscopes are also disclosed in U.S. Pat. No. 4,828,389 of Gubbins et al. covering “Integrated Triad Optical Rate Sensor Apparatus,” and U.S. Pat. No. 5,260,768 of Cordova, et al. covering “Fiber optic gyro with low-birefringence and PM networks”. Despite these advances, further improvements are needed.